1. Field of the Invention
This invention relates to an integrated circuit device and a wire-bonding method for bonding a bounding pad unit on an integrated circuit chip to a contact unit on a substrate, such as a lead frame or a printed circuit board.
2. Description of the Related Art
FIGS. 1 to 4 illustrate a conventional integrated circuit device and a wire-bonding method for forming the integrated circuit device via a wire bonder (not shown). The integrated circuit device includes a substrate 15 with a contact unit 321, an integrated circuit chip 31 with a bonding pad unit 311, and a bonding wire 14 attached to the bonding pad unit 311 and the contact unit 321. The wire bonder includes a capillary head 11 that feeds the bonding wire 14, and forms the bonding wire 14 with a solder ball 13 that is attache d to the bonding pad unit 12 during the wire bonding operation (see FIG. 2). The capillary head 11 then moves along a trajectory (see FIG. 4) such that the bonding wire 14 is configured to have a first extension section 32 that extends upwardly in a direction substantially perpendicular to a plane of the substrate 15, and a second extension section 33 that has a first segment 331 extending downwardly and curvedly from the first extension section 32, and a second segment 332 extending downwardly and inclinedly from the first segment 331 toward the contact unit 321 and attached to the contact unit 321 via stitch bonding (see FIG. 3). The trajectory of the capillary head 11 includes a first linear path 3A that extends upwardly from the solder ball 13 in a direction substantially perpendicular to the plane of the substrate 15, a second linear path 3B that extends from the first linear path 3A in a direction substantially parallel to the substrate 15 away from the contact unit 321, a third linear path 3C that extends upwardly from the second linear path 3B in a direction substantially perpendicular to the plane of the substrate 15, and a fourth path 3D that extends downwardly and curvedly from the third linear path 3C to the contact unit 321.
The whole configuration of the aforesaid bonding wire 14 permits the bonding wire 14 to possess a high wire strength. Moreover, the first extension section 32 extends upwardly from the solder ball 13 to a level that permits the second extension section 33 to be spaced apart from the integrated circuit chip 31 at a distance that is sufficient to prevent the bonding wire 14 from contacting the integrated circuit chip 31 when the bonding wire 14 is turned downwardly and inclinedly from the first extension section 32 toward the contact unit 321 during formation of the second extension section 33. However, such configuration of the bonding wire 14 is disadvantageous in that it is not feasible to attach two or more bonding wires, which are to be fed from the capillary head 11, to the solder ball 13 due to interference of the first extension section 32 with the capillary head 11. While, additional bonding wires can be attached to the bonding pad unit 311 at positions that are spaced apart from the solder ball 13 in order to avoid the aforesaid interference, such arrangement would enlarge the size of the bonding pad unit 311 and affect adversely design flexibility of an integrated circuit chip.
Therefore, the object of the present invention is to provide an integrated circuit device that includes one or more bonding wires attached to a contact unit on a substrate, such as a lead frame or a printed circuit board, and to a electrical bonding contact attached to a bonding pad unit on an integrated circuit chip.
Another object of the present invention is to provide a wire-bonding method that is suitable for attaching one or more bonding wires to a contact unit on a substrate, such as a lead frame or a printed circuit board, and to a electrical bonding contact attached to a bonding pad unit on an integrated circuit chip.
According to one aspect of the present invention, an integrated circuit device comprises: a substrate having a top side provided with a contact unit; an integrated circuit chip mounted on the substrate and having a top side formed with a bonding pad unit; and a bonding wire interconnecting the bonding pad unit and the contact unit, and having a electrical bonding contact attached to the bonding pad unit, a first extension portion extending from the electrical bonding contact in a direction that inclines slightly and upwardly relative to a plane of the substrate toward the contact unit, and a second extension portion extending from the first extension portion and attached to the contact unit.
According to another aspect of the present invention, a wire-bonding method for bonding a bonding pad unit on an integrated circuit chip to a contact unit on a substrate via a wire bonder that includes a capillary head, comprises the steps of: feeding a bonding wire via the capillary head; forming the bonding wire with a electrical bonding contact that is attached to the bonding pad unit; moving the capillary head along a trajectory such that the bonding wire has a first extension portion extending from the electrical bonding contact in a direction that inclines slightly and upwardly relative to a plane of the substrate toward the contact unit, and a second extension portion extending from the first extension portion toward the contact unit; and attaching the second extension portion to the contact unit.